The hard bulge in the stomach in the fourth month of pregnancy, this situation belongs to the fetal activity, in the process of fetal movement will appear bulge phenomenon, this belongs to the normal performance, from the fourth month, the fetus will move on its own, this situation will continue to appear in the whole pregnancy, should be between 4-6 times per hour fetal movement, this belongs to the normal range. If the number of fetal movements decreases or if the number of fetal movements exceeds 6, it is an abnormal phenomenon and should be checked promptly to determine. In general, the number of fetal movements may increase during uterine contractions, but it can return to normal or be relieved after rest, and some patients also have a rapid heart rate during fetal movements, which can return to normal after rest, so there is no need to worry too much.